(1) Field of the Invention
This invention relates to dyeing of cotton yarns for denim. Specifically, this invention is concerned with a dye or dye composition suitable for use in dyeing cotton yarns such as denim warp yarns, a process for dyeing cotton yarns with the dye or dye composition, and a product dyed with the dye or dye composition.
(2) Description of the Related Art
Denim has found wide-spread utility in work clothing, ladies' trousers, children's apparel, etc. for its feeling of cotton to touch, durability and the like as a fabric for clothing.
Jeans made of such denim have been used widely for many years as clothing called "blue jeans". Such popularization of blue jeans has occurred for the following reasons. The characteristic shade of the fabric dyed with an indigo dye and its changes along the passage of time are favored. In addition, it is feasible to develop apparel while placing importance on fashion by making use of the above changes in shade.
Reflecting the recent diversification and expression of individuality in fashion, the demand has increased not only for blue jeans but also so-called color jeans such as yellow, green and black jeans. It is hence desired to color denim, a fabric for jeans, in various shades which range from a yellow or green color to a black color.
Sulfur dyes, vat dyes, reactive dyes and naphthol dyes are used to dye warp yarns for color denim so as to meet the popularization of color jeans.
Color jeans dyed using these dyes are however different in various properties from those dyed with indigo, and their values as goods ranging from dyed fabric to apparel are hence different from those of conventional jeans.
As mentioned above, blue jeans are favored as clothing owing to their characteristic color and various other properties inherent to them. Such properties are also desired for color jeans. Such properties are however not available from products dyed with sulfur dyes, vat dyes, reactive dyes, naphthol dyes or the like.
For example, blue jeans rope dyeing machines have conventionally been used widely to dye cotton yarns with indigo dyes. It is however difficult to apply such machines for dyeing cotton yarns with the above-mentioned dyes, since the dyeing and coloring behavior of these dyes are different significantly from that of indigo dyes. Moreover, effects of decoloration can hardly be expected from the bleaching of these dyes with chlorine. When bleaching is applied to black denim comprising warp yarns dyed in a black color with a dye composition of indigo and a conventional yellow threne dye, the blue color alone is decolored to allow the yellow color to remain so that the commercial value is impaired considerably. Namely, a rope-dyed product which has been dyed with a mixture of an indigo dye and another dye such as sulfur, vat, naphthol or reactive dye can scarcely expect such fading effects as those available with blue denim and is much less attractive from the standpoint of commercial value, because when bleached with chlorine, said another dye undergoes very little decoloration unlike the indigo dye.
As described above, there has still not been reported any dye which shows dyeing and coloring behavior similar to indigo and has similar properties. There is hence neither a dyeing process of cotton yarns making use of a novel dye having such properties nor cotton denim dyed with the novel dye or color jeans using such denim.